Sivut kuvina

Proceedings of the American Academy of Arts and Sciences.

VOL. XLVIII. No. 4.-JULY, 1912.








Presented by R. Thaxter. Received, June 16, 1912.

FOR a considerable time the writer has been engaged in the preparation of an illustrated monograph of the genus Chaetomium but owing to unavoidable interruptions, and delay caused by the preparation of plates, he has thus far been obliged to defer a final publication.

At the time when this work was begun, the only comprehensive paper on the subject was the well known monograph of Zopf (Nova Acta Acad. Leop.-Carol. 42. 1881), but after it was well under way a paper by Bainier appeared in the Bull. de la Soc. Myc. de France (Vol. XXV. Fasc. 4. p. 191. 1910) in which a considerable number of new forms were described and illustrated, some of which prove to be American. Up to the present time, however, there has been no further attempt to make a comprehensive review of the genus or to collate the American forms with the exception of the revision of the Chaetomiaceae in volume III of the "Flora of North America" by H. L. Palliser, who enumerates seventeen species including three unpublished names.

In the course of his work upon these widely distributed fungi the writer has been able to examine a very large series of specimens from various herbaria and exsiccati, and to cultivate many species from diverse sources on various media and through many successive generations. As a result of this examination numerous forms have been added to those previously recorded from America, and a number of new species have been recognized of which it seems desirable to publish the following preliminary diagnoses. In this connection it may be mentioned that all of these forms with two exceptions have been extensively cultivated in a pure condition and that it has been possible to determine with accuracy their range of variation as well as their salient, specific characteristics.

Chaetomium subspirale, sp. nov.

Griseum vel roseo-griseum. Peritheciis majoribus, longioribus, 314 X 213 μ (300-337 × 206-224), sporidiis irregulariter conglobatis gerentibus; pilis lateralibus numerosis, tenuibus, regulariter et distincte septatis, levibus, basi rectis, apice arcte spiraliter convolutis; pilis terminalibus tenuibus, obscure septatis, pallide-olivaceis, levibus, primum arcte dein laxe spiraliter convolutis; ascis clavatis, octosporis, 45 X 9.7 μ, p. sporif. 24 μ; sporidiis subdistichis, pallide olivaceis, limoniiformibus, utrinque apiculatis, 6.4 X 5.2-5.6 μ.

Frequent in cultures of various substrata from New England. Appearing in cultures of dung from Holland and South America.

The species may be distinguished by its characteristic hairs; the lateral ones of which are short, straight, dark below; tightly coiled, hyaline and refractive at the tips; the terminal slender, at first tightly coiled in a delicate spiral, later elongated, twisted rather than coiled and giving the appearance of wooly threads.

Chaetomium sphaerale, sp. nov.

Griseo-flavis, olivaceo-flavis, aetate aureo-flavis. Peritheciis majoribus, subglobosis, basi rotundatis, apice subconstrictis, 312 276 μ (300-329 × 262-300), sporidiis regulariter conglobatis gerentibus vel cirrhis instructis; pilis lateralibus numerosis, gracilibus, levibus, regulariter et distincte septatis, successive olivaceis, aureoflavis, pallide flavis, hyalinis, apice collabentibus; aliis subrectis, longioribus, 1-2-ramosis, basi 3.7 μ diam., aliis flexuosis, brevioribus, non ramosis, basi 2.8 μ diam.; pilis terminalibus longis, gracilibus, pilis lateralibus concoloribus, levibus, irregulariter flexuosis vel subspiraliter convolutis, 1-5-ramosis, basi distincte septatis, apice obscure septatis vel subcontinuis; ascis clavatis, octosporis, 48 X 13 μ, p. sporif. 26 μ; sporidiis subdistichis, dense olivaceo-brunneis, utrinque umbonatis, limoniiformibus, 7.3-8.1 × 6.4 μ.

In a culture of caterpillars from Reading, Mass.

The perithecium, globose below, with a tendency to narrow above into a neck, distinguishes this species from all others which the writer has studied. The slender delicate hairs and the entire absence of differentiated rhizoids are also significant characteristics.

Chaetomium quadrangulatum, sp. nov.

Griseum. Peritheciis majoribus, longioribus, 403 × 294 μ (333– 456 X 243-350), cirrhis longissimis instructis; pilis lateralibus numerosis, tenuibus, rectis, regulariter et distincte septatis, basi olivaceo-fuscis, asperulis vestitis, apice hyalinis, levibus; pilis terminalibus biformibus, aliis spiraliter convolutis, irregulariter pauciseptatis, asperulis vestitis, basi olivaceo-brunneis vel atris, apice dilute coloratis, aliis subrectis, undulatis vel convolutis, irregulariter pauciseptatis, asperulis vestitis, ramosis, basi olivaceo-brunneis vel atris, apice dilute coloratis; ascis clavatis, octosporis, 39 × 9.7 p. sporif. 21 μ; sporidiis pallide olivaceis, a fronte visis subquadrangulatis, a latere ovatis, 7.3 X 6.3 μ (6.4-8 × 5.6-6.4).

Cultivated on dung from Cambridge, Mass. Appearing also on dung from Chile and from Little Swan Island, Gulf of Mexico (R. Thaxter).

The species may be easily identified by the spores which, when seen in face view, are four sided and four angled but, when seen in profile, are oval. Chaetomium quadrangulatum and Chaetomium trigonosporum are the only species known to the writer which possess spores with angles, the former having spores clearly quadrangular, the latter clearly triangular.

Chaetomium convolutum, sp. nov.

Cyano-griseum. Peritheciis magnitudine mediis, globosis, 244 X 232 μ (236-254 X 224-240), cirrhis instructis; pilis lateralibus paucis, gracilibus, rectis, regulariter et distincte septatis, basi olivaceo-flavis, asperulis vestitis, apice hyalinis, sparse asperulis vestitis; pilis terminalibus undique asperulis vestitis, olivaceo-atris, subcontinuis vel irregulariter pauciseptatis, 8-10 spiraliter convolutis, ad ipsam apicem convolutionibus terminalibus regulariter successive minoribus; ascis clavatis, octosporis, 56.4 × 10 μ, p. sporif. 27.4 μ; sporidiis pallide olivaceis, ovatis vel limoniiformibus, utrinque obtusis, subapiculatis, 8-8.4 X 6.4 μ.

Cultivated on mouse dung from Germany.

Apparently a rare species having appeared but once.

The species

may be identified by the distinct blue color of the plant when seen with the naked eye or a hand lens, and by the long spreading terminal hairs whose long series of coils taper abruptly to a blunt point.

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